文件下載和客戶端斷開？

Question

考慮下面的代碼：

async function (req, res, next) { 
    const fd = await fs.open("myfile.txt") 
    fs.createReadStream(null, { fd, autoClose: false }) 
    .on('error', next) 
    .on('end',() => fs.close(fd)) 
    .pipe(res) 
} 

如果客戶端下載整個文件之前斷開，會發生什麼？即end仍然會被調用或是文件描述符泄漏，如果是的話我該如何解決它？如果調用「end」，這是否意味着即使客戶端不再監聽它，整個文件也會被讀取？

請注意，我知道我可以在沒有fd的情況下這樣做，但這是對更復雜代碼的簡化。

Answer 1

它看起來像文件不會關閉，或者至少不會調用您的end事件處理程序。

您可以創建該測試，但這裏是我的：

const http = require('http'); 
const fs = require('fs'); 

var server = http.createServer(function (req, res) { 
    console.log('server request received'); 
    const fd = fs.openSync('myfile.txt', 'r'); 
    fs.createReadStream(null, { fd, autoClose: false }) 
     .on('error', err => { 
      console.error('file error', err); 
     }) 
     .on('end',() => { 
      console.log('file end'); 
      fs.close(fd); 
     }) 
     .on('close',() => { 
      console.log('file closed'); 
     }) 
     .pipe(res) 
      .on('error', err => console.error('server stream error', err)) 
      .on('end',() => console.log('server stream end')) 
      .on('close',() => console.log('server stream closed')) 
    ; 
}); 

server.listen(0, 'localhost',() => { 
    const address = server.address(); 

    var req = http.request({port: address.port}, function (res) { 
     res.on('data', data => { 
      console.log('response data'); 
      // Comment next line to read whole file. 
      req.abort(); 
     }); 
     res.on('end',() => { 
      console.log('response ended'); 
      setTimeout(() => server.close(), 1000); 
     }); 
     req.once('abort',() => { 
      console.log('request aborted'); 
     }); 
    }); 

    req.end(() => { 
     console.log('request sent'); 
    }); 
}); 

我刪除異步/等待運行測試的簡單性。

當req.abort()叫，我得到以下的輸出：

request sent 
server request received 
response data 
request aborted 
response ended 
server stream closed 

評論該行，並允許代碼讀取整個文件後：

request sent 
server request received 
response data 
response data 
response data 
response data 
response data 
response data 
file end 
response data 
response ended 

來創建測試myfile.txt我用下面的命令：

dd if=/dev/zero of=myfile.txt bs=1k count=200